Add unit tests for SyslogUtils

[karimbabasf]

Description

Adds unit test coverage for SyslogUtils, which previously had no tests. This is a test-only change — no production code is modified.

Motivation and Context

SyslogUtils provides the RFC 5424 syslog severity/facility name lookups (levelToString, facilityToString) and the priority decomposition helpers (levelFromPriority, facilityFromPriority) used by the pipeline processor's syslog functions. It had no test coverage, so a future change could silently break the RFC 5424 mappings without any test failing. These characterization tests pin the documented behavior.

How Has This Been Tested?

Added SyslogUtilsTest (JUnit 5 + AssertJ, matching the module's house style). 51 parameterized cases:

• all severities 0–7 map to the RFC 5424 names, and out-of-range values (incl. Integer.MIN/MAX_VALUE) return "Unknown";
• all facilities 0–23 map to their names, and out-of-range values return "Unknown";
• priority decomposition, including the two RFC 5424 worked examples (PRI 34 → auth/Critical, PRI 165 → local4/Notice);
• a round-trip property check confirming facility * 8 + level == priority for every valid PRI value 0–191.

All 51 cases pass locally.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Test-only change: adds coverage for existing behavior, no functional change.

Checklist

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• My change requires a change to the documentation. (n/a — test-only)

[CLAassistant]

All committers have signed the CLA.